☣️ UN 3357 • CLASS 3
UN 3357 — Nitroglycerin mixture, desensitized, liquid, n.o.s., with not more than 30% nitroglycerin
Placard: Flammable. ERG Guide 113. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
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⚠️ Verification required:
Broad or variable material category; verify exact product, SDS and shipping papers.
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
UN 3357 covers liquid nitroglycerin mixtures desensitized with solvent or diluent. The liquid form may still leave dangerous dried residue.
Hazard overview: The mixture is flammable and may become much more sensitive if the desensitizer separates, evaporates or dries. Dried residue must be treated as explosive.
Response guidance: Isolate the area, prevent ignition, avoid impact or friction and keep unnecessary personnel away. Use compatible agents and avoid high-pressure streams that spread liquid.
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UN 3357 Quick Details
UN 3357
Product name: Nitroglycerin mixture, desensitized, liquid, n.o.s., with not more than 30% nitroglycerin
DOT Class: 3
Placard type: Flammable
ERG Guide: 113 (check current ERG)
Initial isolation: ERG 113: isolate spill 50m all directions; evacuate 800m downwind if large spill; treat any dried material as high explosive
Common Hazards of UN 3357
- Flammable/combustible material.
- May be ignited by heat, sparks or flames.
- DRIED OUT material may explode if exposed to heat, flame, friction or shock; treat dried material as an explosive.
- Keep material wet with water or treat as an explosive (GUIDE 112).
- Runoff to sewer may create fire or explosion hazard.
- Some are toxic and may be fatal if inhaled, ingested or absorbed through skin.
- Contact may cause burns to skin and eyes.
- Fire may produce irritating, corrosive and/or toxic gases.
Chemical Identity & Physical Properties
UN 3357 is typically an oily colorless to pale yellow liquid diluted with a desensitizing solvent; dried residue is the critical concern.
| Also known as | Desensitized nitroglycerinNG solutionNitroglycerin liquid mixtureGlyceryl trinitrate mixtureDesensitized dynamite oil |
| Appearance | Oily colorless to pale yellow liquid, typically diluted with a desensitizing solvent. Low volatility but dangerous dried residue may remain. |
| Flash Point | Approximately 13C (55F) for typical desensitized mixtures |
| Boiling Point | 160C (320F) with decomposition - rarely reaches boiling point as it decomposes |
| Vapor Density | Not applicable (low volatility liquid) |
| Water Reactivity | No significant reaction with water, but desensitizer may separate allowing nitroglycerin to concentrate |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 3357
Extinguishing Media
Alcohol-resistant foam, CO2, dry chemical - avoid high-pressure water streams that may spread liquid
PPE Requirements
⚠️ Level B minimum with full face SCBA; nitrile or butyl rubber gloves; avoid any impact or friction to dried residue
Use Level B with SCBA, chemical-resistant gloves and full protective clothing. Treat dried or heated material as explosive.
Isolation & Evacuation
ERG 113: isolate spill 50m all directions; evacuate 800m downwind if large spill; treat any dried material as high explosive
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 113).
First Actions for a UN 3357 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- Isolate spill or leak area immediately for at least 100 meters (330 feet) in all directions.
- Consider initial evacuation for 500 meters (1/3 mile) in all directions.
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📋 Copy & Share Field Card
UN 3357 — Nitroglycerin mixture, desensitized, liqHAZMAT RADIO NOTE — UN 3357
Product: Nitroglycerin mixture, desensitized, liquid, n.o.s., with not more than 30% nitroglycerin
Class 3 / Flammable / ERG 113
PPE: Level B minimum with full face SCBA; nitrile or butyl rubber gloves; avoid any impact or friction to dried residue
ISOLATION: ERG 113: isolate spill 50m all directions; evacuate 800m downwind if large spill; treat any dried material as high explosive
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 3357 — Nitroglycerin mixture, desensitized, liquid, n.o.s., with not more than 30% nitroglycerin
Class: 3 | Placard: Flammable | ERG Guide: 113
Appearance: Oily colorless to pale yellow liquid, typically diluted with a desensitizing solvent. Low volatility but dangerous dried residue may remain.
Water Reactivity: No significant reaction with water, but desensitizer may separate allowing nitroglycerin to concentrate
Extinguishing: Alcohol-resistant foam, CO2, dry chemical - avoid high-pressure water streams that may spread liquid
PPE: Level B minimum with full face SCBA; nitrile or butyl rubber gloves; avoid any impact or friction to dried residue
Isolation: ERG 113: isolate spill 50m all directions; evacuate 800m downwind if large spill; treat any dried material as high explosive
— Key Hazards —
• Flammable/combustible material.
• May be ignited by heat, sparks or flames.
• DRIED OUT material may explode if exposed to heat, flame, friction or shock; treat dried material as an explosive.
— First Actions —
• CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/nitroglycerin-mixture-desensitized-liquid-un-3357 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
UN3357 Nitroglycerin mixture, desensitized, liquid, n.o.s., with not more than 30% nitroglycerin Cls3 ERG113 | allfirefighter.com/hazmat/un/nitroglycerin-mixture-desensitized-liquid-un-3357SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/nitroglycerin-mixture-desensitized-liquid-un-3357
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Frequently Asked Questions about UN 3357
UN 3357 is a desensitized liquid nitroglycerin mixture with not more than 30% nitroglycerin.
Yes. It is a flammable liquid entry.
Drying can reduce desensitization and make residue shock- or friction-sensitive.
Avoid heat, sparks, friction, impact and high-pressure water streams.
SCBA with Level B protection and chemical-resistant gloves is recommended.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles.
This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.